D3D11 Debug Layer的bug

在开发D3D应用程序时，我们会使用Debug Layer来调试应用程序，以确保我们的程序在最终发布时没有warnings和errors。不过最近在开发应用程序时遇到了这样的问题，就是我把多个网格模型的顶点数据放在一个vertex buffer中，与此同时也把它们的索引数据放在一个index buffer中，然后在绘制不同的网格模型时就需要设置相应的偏移量，代码看上去是这样的：

首先我创建了一个box和一个grid：

CGeometryGenerator::CreateBox( 1.0f, 1.0f, 1.0f, box );
CGeometryGenerator::CreateGrid( 20.0f, 30.0f, 50, 40, grid );

接着我记录下每个网格模型的顶点偏移量和索引偏移量：

g_uBoxVertexOffset = 0;
g_uGridVertexOffset = g_uBoxVertexOffset + box.vertices.size();

g_uBoxIndexCount = box.indices.size();
g_uGridIndexCount = grid.indices.size();

g_uBoxIndexOffset = 0;
g_uGridIndexOffset = g_uBoxIndexOffset + g_uBoxIndexCount;

最后我将box和grid的顶点数据与索引数据存放在一个vertex buffer和index buffer中：

// Copy vertices
UINT uVertexCount = box.vertices.size() + grid.vertices.size() + sphere.vertices.size() + cylinder.vertices.size();
std::vector<VertexPositionNormal> vVertices( uVertexCount );
UINT uVertexIndex = 0;

for ( UINT vertexIndex = 0; vertexIndex < box.vertices.size(); ++vertexIndex, ++uVertexIndex )
{
    VertexPositionNormal &vertex = vVertices[uVertexIndex];
    VertexPositionNormalTangentColorTexture &boxVertex = box.vertices[vertexIndex];
        
    vertex.position = boxVertex.position;
    vertex.normal = boxVertex.normal;
}

for ( UINT vertexIndex = 0; vertexIndex < grid.vertices.size(); ++vertexIndex, ++uVertexIndex )
{
    VertexPositionNormal &vertex = vVertices[uVertexIndex];
    VertexPositionNormalTangentColorTexture &gridVertex = grid.vertices[vertexIndex];
        
    vertex.position = gridVertex.position;
    vertex.normal = gridVertex.normal;
}

// Create vertex buffer
{
    D3D11_BUFFER_DESC vertexBufferDesc;
    vertexBufferDesc.Usage = D3D11_USAGE_IMMUTABLE;
    vertexBufferDesc.ByteWidth = sizeof(VertexPositionNormal) * uVertexCount;
    vertexBufferDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER;
    vertexBufferDesc.CPUAccessFlags = 0;
    vertexBufferDesc.MiscFlags = 0;
    vertexBufferDesc.StructureByteStride = 0;

    D3D11_SUBRESOURCE_DATA subresourceData;
    subresourceData.pSysMem = &vVertices[0];
    subresourceData.SysMemPitch = 0;
    subresourceData.SysMemSlicePitch = 0;

    HRESULT hr;
    V( pD3DDevice->CreateBuffer(&vertexBufferDesc, &subresourceData, g_pShapeVertexBuffer.ReleaseAndGetAddressOf()) );
}

// Create indices
UINT uIndexCount = g_uBoxIndexCount + g_uGridIndexCount;

std::vector<UINT> vIndices;
vIndices.insert( vIndices.end(), box.indices.begin(), box.indices.end() );
vIndices.insert( vIndices.end(), grid.indices.begin(), grid.indices.end() );

// Create index buffer
{
    D3D11_BUFFER_DESC indexBufferDesc;
    indexBufferDesc.Usage = D3D11_USAGE_IMMUTABLE;
    indexBufferDesc.ByteWidth = sizeof(UINT) * uIndexCount;
    indexBufferDesc.BindFlags = D3D11_BIND_INDEX_BUFFER;
    indexBufferDesc.CPUAccessFlags = 0;
    indexBufferDesc.MiscFlags = 0;
    indexBufferDesc.StructureByteStride = 0;

    D3D11_SUBRESOURCE_DATA subresourceData;
    subresourceData.pSysMem = &vIndices[0];
    subresourceData.SysMemPitch = 0;
    subresourceData.SysMemSlicePitch = 0;

    HRESULT hr;
    V( pD3DDevice->CreateBuffer(&indexBufferDesc, &subresourceData, g_pShapeIndexBuffer.ReleaseAndGetAddressOf()) );
}

因此，在绘制grid时，我就需要设置相应的偏移量来保证读取的顶点和索引数据是正确的，代码如下：

pD3DImmediateContext->DrawIndexed( g_uGridIndexCount, g_uGridIndexOffset, g_uGridVertexOffset );

这个时候，D3D Debug Layer就会出现错误：

起初以为是偏移量设置出错，但是仔细检查了代码，发现没有任何问题，同时渲染结果也是正确的。于是，尝试采用另一种方式，就是在设置vertex buffer时设置偏移量：

UINT stride = sizeof( VertexPositionNormal );
UINT offset = g_uGridVertexOffset * sizeof(VertexPositionNormal);
pD3DImmediateContext->IASetVertexBuffers( 0, 1, g_pShapeVertexBuffer.GetAddressOf(), &stride, &offset );

pD3DImmediateContext->DrawIndexed( g_uGridIndexCount, g_uGridIndexOffset, 0 );

此时错误就消失了，渲染也是正确的，也就是说，代码中的偏移量计算是正确的。

于是上网翻阅了一些资料，发现有不少朋友遇到过这个问题，同时确认这个是D3D Debug Layer的bug，也就是当DrawIndexed函数中的StartIndexLocation和BaseVertexLocation参数同时不为0时，就会出现上图的warning。
既然程序是正确的，那么有什么办法可以不让它打印这个warning呢？一个方法就是上面我提到的，在设置vertex buffer时设置偏移量。还有个办法就是通知Debug Layer隐藏这个消息：

// Hide warning: DEVICE_DRAW_INDEX_BUFFER_TOO_SMALL which is a bug of D3D11 Debug Layer
#if defined(DEBUG) | defined(_DEBUG)
ID3D11Debug *pD3DDebug = NULL;
if( SUCCEEDED(pD3DDevice->QueryInterface(__uuidof(ID3D11Debug), reinterpret_cast<VOID**>(&pD3DDebug))) )
{
    ID3D11InfoQueue *pD3DInfoQueue = NULL;
    if( SUCCEEDED(pD3DDebug->QueryInterface(__uuidof(ID3D11InfoQueue), reinterpret_cast<VOID**>(&pD3DInfoQueue))) )
    {
        D3D11_MESSAGE_ID arrHiddenMessageID[] =
        {
            D3D11_MESSAGE_ID_DEVICE_DRAW_INDEX_BUFFER_TOO_SMALL,
        };
            
        D3D11_INFO_QUEUE_FILTER filter;
        memset( &filter, 0, sizeof(filter) );
        filter.DenyList.NumIDs = ARRAYSIZE( arrHiddenMessageID );
        filter.DenyList.pIDList = arrHiddenMessageID;
        
        pD3DInfoQueue->AddStorageFilterEntries( &filter );
        SAFE_RELEASE( pD3DInfoQueue );
    }
    SAFE_RELEASE( pD3DDebug );
}
#endif